温度对制备Al-Ti-C晶粒细化剂的影响

采用石墨粉加入到Al-Ti合金中的方法来制备Al-Ti-C晶粒细化剂。采用扫描电镜和透射电镜观察了Al-Ti-C合金的微观形貌，采用X射线衍射装置检测了Al-Ti-C合金中的相组成。结果表明，在制备Al-Ti-C合金过程中，温度低于1273K先生成TiC粒子，随着保温时间的延长TiC转变成为Al4C3;但温度升高到1573K以上时,Al4C3会分解重生成TiC.     

原料加入温度对Al-Ti-C晶粒细化剂显微组织的影响

采用K2TiF6、石墨粉和纯铝为主要原料的原位反应方法制备了Al-Ti-C晶粒细化剂.通过光学显微镜、扫描电镜和能谱分析等方法分析了Al-Ti-C中间合金的显微组织.试验结果表明,K2TiF6和石墨粉同温下加入时,Al3Ti呈块状分布,不同温度下加入时则呈针状或长条状分布.随着K2TiF6和石墨粉加入温度的不同,Al-Ti-C中间合金中TiC粒子的生成机制也不同.     

Al-Ti-C中间合金的制备及其在4032铝合金中的应用

采用元素直接合成法,以工业纯铝、钛屑及石墨颗粒为原料制备Al-Ti-C中间合金,研究和评价了Al-Ti-C中间合金的显微组织及其对4032铝合金铸态组织和活塞模锻件组织的影响。结果表明,制备的Al-Ti-C中间合金由Al基体、长条状Al3Ti相和细小粒状TiC相,以及少量的游离C组成。将其应用于4032铝合金中,起到了明显的铸态晶粒细化效果。用该合金制备的活塞模锻件,显微组织和性能优良。     

电弧高温制备Al-Ti-C中间合金

研究了新型Al-Ti-C中间合金的制备方法。电弧高温能使Al与C更好地熔合,解决了Al与C润湿性差的问题。利用SEM、XRD、EDS对制备的Al-Ti-C中间合金进行分析。结果表明,电弧高温下制备的Al-Ti-C中间合金由Al、TiAl_3和TiC组成。经过HF酸处理的石墨、钛粉在电流为75A,铝液温度为800℃条件下与纯铝反应,制备出效果最好的AlTi-C中间合金。     

高性能Cu-Cr-Zr-Mg-RE合金的熔炼

探讨了高性能Cu-Cr-Zr-Mg-RE合金在大气下的熔炼技术。研究结果表明,熔炼过程中采用中频感应炉和陶瓷坩埚,能防止铬和石墨反应形成碳化物,提高了铬的收得率;Cr、Zr等合金元素以中间合金方式加入,并用石墨钟罩压入熔体中,能减少烧损;采用玻璃 硼砂 鳞片石墨的复合覆盖剂能有效地减少合金氧化、吸气及挥发。     

Al—Ti—C中间合金的相组成及其细化特性

用专利方法制备出各种成分的Al-Ti-C中间合金作为铝及铝合金的晶粒细化剂。对该系列中间合金的组织和物相分析表明：在制备中间合金过程中,C与Ti反应充分,生成TiC和TiAl3两种管二相,且TiAl3析出量取决于中间合金的Ti含量和Ti/C含量比。用于纯铝的晶粒细化试验表明：与Al-Ti-C中间合金相比,Al-Ti-C中间合金的晶粒细化效率更高;Al-Ti-C中间合金只有在组织中TiC与TiAl3保持适当比例时,才能对纯铝产生良好的晶粒细化效果,不含TiAl3的Al-Ti-C中间合金的晶粒细化作用很微弱;用Al-Ti-C中间合金细化纯铝晶粒时,响应时间短,但衰退较快,且不能通过熔体搅拌法予以消除。分析和探讨了Al-Ti-C中间合金的晶粒细化机理,认为“碳化物理论” 不能充分解释Al-Ti-C的晶粒细化机理,提出“Ti在TiC或TiAl3颗粒表面富集引发包晶反应”的晶粒细化机制。     

辐照参数对激光引燃自蔓延合成Al-Ti-C中间合金的影响

采用激光引燃自蔓延高温合成技术制备Al-Ti-C中间合金,研究了改变激光辐照参数对合成Al-Ti-C中间合金显微组织结构的影响,并用所制备的中间合金对工业纯铝进行细化试验。结果表明:激光辐照时间为1.0s、功率控制在1000W时,制备的Al-Ti-C中间合金生成TiAl3和TiC粒子弥散分布、TiAl3直径在1.5μm左右,TiC粒子直径为1μm。向工业纯铝中加入0.1%的Al-Ti-C中间合金具有最佳的细化效果,细化后晶粒的尺寸为120μm。     

Al-Ti-C中间合金对Mg-Al合金的晶粒细化作用

制备了一种用于Mg-Al合金晶粒细化的Al-Ti-C中间合金。发现该Al-Ti-C中间合金可以有效地细化镁合金的晶粒，细化后的AZ61合金的抗腐蚀性能大大提高。分析认为，Al-Ti-C中间合金中起晶粒细化作用的是Al4C3和TiC的复合相。     

液固反应法合成Al-Ti-C晶粒细化剂研究

采用液固反应合成技术,通过铝熔体润湿活化与助熔处理的无定型石墨的方法,成功地制备了Al-5%Ti-0.25%C细化剂合金,用SEM、OM及DSC分析手段,研究了该合金的组织特性与熔体反应机制.结果表明:Al-Ti-C细化剂合金组织由Al基体、针状及片状TiAl3相和TiC粒子团簇组成,TiC粒子为非化学计量比化合物,X为0.5～0.8;固-液反应制备Al-Ti-C晶粒细化剂合金过程符合溶解-析出机制.     

石墨与Al-Ti合金反应生成TiC粒子的机理

采用石墨粉加入到Al Ti熔体中的方法来制备Al Ti C晶粒细化剂。用金相显微镜、扫描电镜观察不同反应时间的Al Ti C合金微观组织 ,结合热力学和动力学的分析 ,研究了石墨与Al Ti合金熔体反应生成TiC粒子的机理。结果表明 :在 10 73～ 1173K温度范围内 ,将石墨加入Al 5 %Ti合金熔体中 ,石墨与Al液不会直接反应生成Al4 C3 ,石墨也不会转变成游离的碳原子而与Ti反应生成TiC。TiC由下面反应式生成 :Ti C石墨 →TiC、TiAl3 C石墨 →TiC 3Al     

Effect of nano TiN/Ti refiner on as-cast and hot-working microstructure of commercial purity aluminum

A novel type nano TiN/Ti composite grain refiner (TiN/Ti refiner) was prepared by high energy ball milling, and its effect on as-cast and hot-working microstructure of commercial purity aluminum (pure Al) was investigated. The results show that TiN/Ti refiner exhibits excellent grain refining performances on pure Al. With an addition of 0.2% TiN/Ti refiner, the average grain size of pure Al decreases to 82 μm, which is smaller than that of pure Ti and Al–5Ti–1B master alloy as refiners. The microstructure of weld joint of pure Al with 0.1% TiN/Ti refiner is fine equiaxed grains and the hardness of weld joint is higher than that of the base metal. For pure Al with 40% cold deformation and recrystallization at 250 °C for 1.0 h, the grains of the sample added 0.1% Ti powder have an obvious grain growth behavior. In contrast, oriented grains caused by deformation have been eliminated, and there is no obvious grain growth in pure Al refined with 0.1% TiN/Ti refiner, indicating that nano TiN in the refiner inhibits the growth of grain during recrystallization.     

Synthesis of TiC composite by salt route and grain refinement of aluminium alloy

Abstract

The synthesis of Al–3Ti–0˙75C master alloy grain refiner was carried out by adding K₂TiF₆ and graphite powder together in aluminium melt from 800 to 1200°C. The reaction between the halide salts and graphite in aluminium melt was also carried out at different time intervals at 1200°C. The in situ formation of TiC particles in the Al/K₂TiF₆/graphite system involved the formation of Al₃Ti followed by formation of TiC at varying temperature and time. It is observed that TiC and Al₃Ti phases together showed the best grain refining efficiency in comparison to only by TiC or Al₃Ti alone.     

Effect of heat treatment on microstructures and mechanical properties of A356 alloy cast through rapid slurry formation (RSF) process

The effect of T5 heat treatment on microstructure and mechanical properties of A356 alloy was observed. The as-cast A356 alloy exhibited coarse dendrites and long Si needles. RSF process changed the dendritic α-Al phase to globular morphology which helps in improving the mechanical properties of the alloy. The addition of 0.6wt-% Al–5Ti–1B grain refiner refined the average grain size of primary α-Al phase. T5 heat treatment at 170 °C for 20 h in different processing conditions was given to A356 alloy. T5 heat treatment led to further refinement of α-Al phase and Si needles, precipitation hardening due to Mg₂Si phase and reduction in the porosity level (%). The Quality Index for A356 alloy in different processing conditions was also measured. Results showed that RSF process with the use of baffles, addition of grain refiner and T5 heat treatment had improved the mechanical properties over other processing conditions.     

Al-Ti-C晶粒细化剂制备工艺的研究

利用Al液的高温,使加入其中的Al、Ti、C混合粉末发生SHS反应,制备出了Al-Ti-C中间合金晶粒细化剂,通过扫描电镜（SEM）、光学显微镜（OM）和能谱分析（EDS）等手段,研究了铝粉颗粒大小对制备的Al-Ti-C晶粒细化剂组织结构的影响,考察了制备的Al-Ti-C晶粒细化剂对工业纯Al的晶粒细化效果.结果表明：当铝粉大小为100目～200目的细铝粉时,制备的Al-Ti-C中间合金由块状Al3Ti、粒状TiC和Al基体组成,对工业纯Al具有良好的晶粒细化效果.     

铝钛碳晶粒细化剂的制备及工业应用

提出了利用铝锭、氟钛酸钾、铝粉、六氯乙烷和碳粉制备铝钛碳晶粒细化剂的新方法。研究表明，经过预处理的碳粉．采用预制块压入法可使碳的吸收率稳定在90％左右。用研制的Al—5Ti-0．2C晶粒细化剂在铝合金轮毂和铝铸轧两大铝加工行业进行工业应用试验，效果非常明显，是替代铝钛硼晶粒细化剂的理想产品，具有很好的发展前景。     

Melting purification process and refining effect of 5083 Al–Mg alloy

To improve the poor stability of casting process of Al alloy with high Mg content, which leads to poor final product quality, the melting purification process and the influences of the refiner on the microstructure and defect of 5083 alloy were studied. The results show that the optimized process for the rotary impeller degassing of 5083 alloy is as follows: a rotary speed of 250–400 r/min; a gas flow of 1.2–2.0 L/s, a refining time of 10–15 min. This optimized process can reduce the gas content in the solid alloy to 2×10^?3 mL/g or lower. Due to the addition of grain refiner, the cast microstructure of 5083 alloy is refined. The Al–5Ti–1B wire shows the best refining effect among all the refiners. The refining effect is improved with the increase of grain refiner addition amount. And the refinement effects become stable when Ti content reaches 0.1% or higher. The surface crinkling defect of the billet can be easily found in the alloy refined with Al–5Ti–1B wire compared with the alloys refined with other refiners.     

Effect of TiC Nanoparticles Supported by Ti Powders on the Solidification Behavior and Microstructure of Pure Aluminum

A novel grain refiner consisting of TiC nanoparticles (NPs) supported by Ti powders (abbr. TiC/Ti refiner) was prepared by high-energy milling. The addition of 0.5 wt% TiC/Ti refiner converted the structure of pure Al from coarse dendrites to fine equiaxed grains with the average grain size of 114.7 μm, and it also increased the nucleation temperature of α(Al) from 656.7 to 664.4 °C. When TiC/Ti refiner was introduced into Al melt, the heat released from the Al–Ti reaction promoted the uniform dispersion of TiC NPs. The dissolution of the reaction product TiAl₃ released Ti atoms into the melt and thus formed a “Ti-rich transition region” around TiC NPs. The dispersive TiC NPs could act as the heterogeneous nuclei for α(Al) and the “Ti-rich transition region” further improved the lattice orientation relationship between Al (\(\bar{1}1\bar{1}\)) and TiC (\(11\bar{1}\)) planes, which eventually resulted in the refining of α(Al).     

Al-Ti-B-RE细化剂对Al-7．0Si-0．55Mg合金显微组织和力学性能的影响

研究添加Al-5Ti-lB-RE细化剂对Al-7．0Si-0．55Mg（A357）合金的显微组织和力学性能的影响。先利用真空熔炼技术制各Al-7．0Si-0．55Mg合金,然后在Al-7．0Si-0．55Mg合金中加入不同成分的Al-5Ti-1B-RE中间合金。通过X射线衍射仪（XRD）、金相显微镜（OM）和扫描电子显微镜（SEM）对显微组织和拉伸试样的断口形貌进行观察。在室温下对合金的力学性能进行测试。观察Al-5Ti-1B-RE细化剂的形态以及内部结构,可以发现以TiB,为异质形核核心的TiAl3／Ti2Al20RE的壳层结构相。在Al-7．0Si-0．55Mg合金中加入Al-5Ti-1B-3．0RE细化剂后,抗拉强度会有明显提升,直到0．2％添加量时,抗拉强度会达到峰值。